Background-free quantum frequency conversion of single photons from a semiconductor quantum dot

TL;DR

This paper demonstrates a background-free quantum frequency conversion process for single photons emitted from a semiconductor quantum dot, preserving photon statistics and enabling improved quantum communication applications.

Contribution

It introduces a method for background-free frequency conversion of single photons from quantum dots using a PPLN waveguide with large pump-signal detuning, preserving photon statistics.

Findings

Successful conversion of 980 nm photons to 600 nm with minimal background

Preservation of photon statistics after conversion

Potential for improved quantum communication systems

Abstract

We demonstrate background-free quantum frequency conversion of single photons from an epitaxially-grown InAs quantum dot. Single photons at \approx 980 nm are combined with a pump laser near 1550 nm inside a periodically-poled lithium niobate (PPLN) waveguide, generating single photons at \approx 600 nm. The large red-detuning between the pump and signal wavelengths ensures nearly background-free conversion, avoiding processes such as upconversion of anti-Stokes Raman scattered pump photons in the PPLN crystal. Second-order correlation measurements on the single photon stream are performed both before and after conversion, confirming the preservation of photon statistics during the frequency conversion process.